#include <iostream>
#include <fstream>
#include <vector>
#include <string>
#include <algorithm>
using namespace std;

int main(){


  int n; cin >> n;
  vector<int> w1(n + 1,0),w2;
  for (int i = 0; i < n; i++) {
    for (int j = 0; j < n; j++) {
      string a; cin >> a;
      if (a == "nyanpass") {
        w1[j]++;
      }
    }
  }
  for (int i = 0; i < n + 1; i++) {
    if (w1[i] == n - 1) {
      w2.push_back(i);
    }
  }
  int b = w2.size();
  cout << (b == 1 ? w2[0] + 1 : -1 ) << "\n";

  return 0;
}